In recent years, there has been widely used a system in which an information terminal such as a mobile communication device that has a content playing function and a network function is connected to a server to synchronize content between the information terminal and the server and to distribute content from the server to the information terminal. The purpose of synchronization of content that is described herein is to make the update of the contents in the server and the information terminal in cooperation via a network. For example, if server stores content that is not stored in the information terminal, the content can be distributed from the server to the information terminal at the user's request. Synchronization of content makes it possible for the user to download newly content registered in the server to the information terminal by the network.
Also, patent document 1 discloses a technology relating to synchronization of content. The technology disclosed in patent document 1 is to prevent content that was once distributed to, but deleted at, an information terminal, from being distributed to the information once again. In the information terminal described in patent document 1, “deleted” files and “undistributed” files are managed distinctively.